Increasing prevalence of diabetes mellitus in association with fatty liver in a Japanese population

Background The prevalence of diabetes mellitus (DM) has been increasing. The present study was carried out to examine the relationship between this increase and fatty liver. Methods Japanese participants who underwent regular health examinations in 1991, 1996, 2001, 2006, and 2011 were enrolled. Fatty liver was diagnosed using ultrasonography. DM was defined as requiring the use of medication for DM, having a fasting blood glucose level >= 126 mg/dl, or hemoglobin A1c level >= 6.5 %. Results Logistic regression analysis on data from 11,235 participants (6,882 men and 4,271 women) in 2011 revealed that the association between fatty liver and DM was independent of age, body composition, and other confounders [odds ratio (OR) 1.97, 95 % confidence interval (95 % CI) 1.66-2.32 in men, and OR, 3.12; 95 % CI, 2.29-4.26 in women]. In 2006, 5,318 participants did not have DM and were able to be followed up in 2011. Fatty liver in 2006 was an independent predictor of DM in 2011 [OR 1.73 (95 % CI 1.20-2.50) in men, 4.13 (2.16-8.10) in women]. The prevalence of DM increased significantly during the 20-year period examined among both men (6.0, 8.9, 10.0, 10.8, 12.0 %, P<0.001) and women (3.3, 4.5, 4.2, 4.1, 5.1 %, P = 0.004), accompanied with an increased prevalence of fatty liver among both men (10.8, 26.3, 33.8, 36.7, and 38.0 %, P< 0.001) and women (6.5, 16.7, 22.2, 21.3, and 20.8 %, P< 0.001). Conclusion Fatty liver independently predicts both present and future DM. Fatty liver may play an important role in the recent increases in the prevalence of DM.